<!DOCTYPE html>
<html>
	<head>
		<meta charset="UTF-8">
		<title></title>
	</head>
	<body>
		<script type="text/javascript">
			var price =prompt("请输入商品价格");
			alert("优惠后价格为："+price*0.8);
		</script>
	</body>
</html>
